How Do Activators Work

Question 1

What is a core enzyme?

Answer 1

CORE ENZYME=2 alpha, 1 beta, beta’ subunit

-highly homologous to all RNA polymerases including bacterial, archaeal, and eukaryotic

Question 2

What is a holoenzyme?

Answer 2

HOLOENZYME=sigma + core factor

Question 3

Sigma/Promoter relationship

Answer 3

SIGMA recognizes the promoter (interaction 1)

• SIGMA is involved in BOTH close and open complex formation
• SIGMA has homologs in archaea and eukaryotes
• these homologs bind the TATA box (the eukaryotic promoter)

Question 4

Who is this alpha cat?

Answer 4

• alpha is a dimer that has 2 domains
• alpha-NTD helps to assemble the core enzyme
• alpha-CTD connected to alpha-NTD by a flexible linker
• alpha-CTD binds DNA (interaction 2) involved in closed complex formation
• alpha-CTD interacts with sigma (interaction 3) involved in open complex formation

Question 5

Are they in the CR(i)P(s)

Answer 5

• CRP is a dimer
• when bound by cAMP, CRP binds DNA
• cAMP-CRP complex is involved in closed complex formation
• CRP interacts with alpha-CTD-involved in closed complex formation